Iron removal from aldehyde synthesis process



July 22, 1952 c. H. HALE IRON REMOVAL FROM ALDEHYDR sYNTRRss PROCESS Filed April 1, 1949 Omi 9 @Q I @el OO:

ON@ wozmoouQ/I Ll 7 @UNL ZTLMJO mwdja im, @nw N .v Edkmh@ N1 6m l@ dmmoumnwl A li (dmkfu OQ Iv :Nw h\lX/v a mumm l T. 3u (N. Nm: e ,fl/lm GWW Om :bv uowMmMI/v W LI.. L.I\ Gm umdimm dmb R fu. Tl GT www mk, dmjaumk Ll N Ceci- H-Halle b5 Gbncne @rm/eater Patented July 22, 1952 IRON REMOVAL FROM SYNTHESIS PROCESS Cecil I-I. Hale, lBaton Rouge, La., assigner 'to Standard 'Oil Development Company,`a corporation of IDelaware .Application April :1, 1949, Serial No. 84,'878

The present invention relates `to 4.the preparation .of -oxygenated organic compounds by the -reaction of carbon monoxide and hydrogen with carbon compounds containing olenic linkagesin the presence of a carbonylation catalyst. More specifically, this invention relates to vanimproved process .for .removing catalytic material yfrom the reaction products .resulting from vthe interaction of olenic -compounds withcarbon monoxide and hydrogen. i

It is now .Well known .in the art that oxygenated organic compounds may be synthesized from organic compounds containing olenic linkages by a reaction with .carbon monoxide and .hydrogen in .the presence of .a-catalyst containing metals 'of the iron group, such as cobalt vor iron, Vpreferably the former, in an essentially three-stage process. In the vfirst stage, the oleflnic material, catalyst and theproper proportions of CO and H2 4are .reacted -to Vgive a product consisting .predominantly of aldehydes containing one more carbon atom than thereacted olefin. This oxygenated organic mixture, which contains .dissolved init salts'and the carbonylsand .molecular complexes of the metal catalyst, is treated in a second stage to cause. removal of soluble .metal compounds 'from the organic material in a catalyst removal zone. The catalyst-free material is then .generally hydrogenated to the corresponding alcohols, or may beoxidized to the corresponding acid.

HThis'carbonyl'at'i'o'n reaction provides .aipar'ticularly attractive .method for Vpreparing valuable primary alcoholswhich find large markets, particul'arlyvas intermediates for ,plasticizers detergentsan'd'so'lvents. Amenable 'to the reaction are long Iand -short 'chained olefinic compounds, depending upon the type alcohols desired. 4Not only pleins, but most organic compounds possessing atleast one non-'aromatic carbon-carbon double Abond may be reacted by this method. Thus straight and branch chained oleins and diolens'su'ch'as propylene, butyl'ene, pentene, hexene',fhep'tene, `butadiene, pentadienestyrene, 'olefin polymers such as diand tri-isobutylene and hexene and'heptene dimers, polypropylene, .olenicffractions from the hydrocarbon synthesis process; thermal or ycatalytic cracking operations, and Iother sources of 'hydrocarbon fractions containing olens may be used as starting material, depending upon the nature of 'the final product desired.

The catalyst in the first `stage of the process is usually added v'in the form 'of salts of 'the catalytically 'active metal with 'high 'molecular fatty acids, :such as steari'C, oleic, palmitic, naphthenic,

etc., acids. Thus suitable catalysts .are, for example, `cobalt -oleate or naphthenate, or iron linoleate. These .salts are soluble .in the liquid olenn .feed and -may be supplied to the 4iirststage .as hydrocarbon .solution or dissolved in theolen feed.

The synthesis gas mixture fed to the irst stage .mayconsist of .anyra-tio of H2 to CO, .but preferably these .gases are .present in about .equal vollabout V1.500 to 4500 p. s. i.. g. and at temperatures in the range of about 150g-450 F. The .ratio vof synthesis gas to olen .feed may vary widely; in

generaLabout 2500 -to 15,000 cubic Vfeet of Hz-l-CO per barrel of olen feed are employed.. f

At .the end .of the .rst stage, when -theudesired conversion of olens to oxygenated compounds has been effected, the product andthe .unreacted material are generally withdrawn to ,a .catalyst removal zone, where dissolved catalystis .removed from the mixture, and it is to this stage thatthe present invention applies.

One of the major problems involved in the aldehyde synthesis reaction is the fact that the catalyst metal and other carbonyl forming metals such as cobalt, iron, etc., though Iadded as `organic salts to the reaction zone, react with carbon monoxide under the synthesis `conditions to Lform metal carbonyls. There is basis for the ubelief that the metal carbonyl or Ahydrocarbonyl .is-the active v'form of the catalyst. The carbonyl remaining dissolved in the reaction .product from the .primary carbonylation vstageV can Kthen be removed in an intermediate catalyst removal stage and this is customarily done Aby heating the .primary 'reaction 'product inV a suitable chamber or tower with .or without packing at atmospheric or superatmo'spher'ic pressures and usually in fthe presence of a slow stream of an inert stripping gas such as hydrogen in order to remove overhead thefcarbon monoxide resulting from the Ydecomposition of the metal carbonyl to protect the niekelor cobalt or othercarbonyl formingmetal employed 4-in` the subsequent high 'pressure hydro;- genation stage. IThough this process isquite satisfactory as far as Aremoving the cobaltvcarbonyl is concerned by decomposing the latter into metallic cobalt and carbon monoxide, and though the soluble cobalt in the primary reaction product may be substantially removed, small quantities of other metallic carbonyls, .in'particular .iron carbonyl, are not completely removed by this process. Iron carbonyl arises from various sources such as from the interaction of carbon monoxide at high pressures with iron-containing impurities in the feed, reaction of carbon monoxide with the walls of the reactor and transfer lines, reactor packing, and the like. Iron carbonyl is considerably more stable than the cobalt analogue and thus While the latter is decomposed under decobalting conditions in the catalyst re'- moval zone, or decobalter, iron carbonyl is only partially decomposed. Thus while the concentration of soluble cobalt leaving the catalystremoval zone after treatment described above, may be 0.005% or less, the concentration of soluble iron is often as much as 0.02% or more. It is highly undesirable for soluble iron to be present in the product leaving the catalyst removal zone because of the tendency for the soluble iron compounds to decompose under the more severe conditions obtaining in the hydrogenation zone and in the preceding heating coils, resulting in plugged lines and also in deactivation of the hy- `drogenation catalyst; accordingly, it is highly desirable to keep the concentration of carbonyls and other soluble metallic compounds and complexes, both iron and cobalt, less than 0.005% in the eluent from the catalyst removal zone.

As a result of the heat treatment of the vprimary reaction product containing in solution the metal carbonyls, CO is evolved as noted above and a precipitate of the metal is formed, the metal being in an extremely nely divided form, existing partly as a suspension, partly as a colloid, requiring for removal a lengthy and costly filtration because of the extremely fine state of subdivision of the particles. j

It is one of the purposes of the present invention to provide improved means for removing iron and other carbonyl-forming metals from the carbonylation reaction product and -to prevent plugging of reactor lines and deactivation of the y hydrogenation catalyst.

Another purpose of the invention is to provide an ecient means for decomposing substantially completely metal compounds present in the carbonylation reaction effluent.

Another purpose of the present invention is to provide a means of removing'i-lnely divided and colloidably dispersed metal solids from suspension in the reaction product.

Other and further objects'and advantages'of the invention will become apparent from the description hereinafter. f

It has now been found that these objects may readily be accomplished and a reaction product obtained substantially free of dissolved or suspended metal by treating the primary reaction product with an alkaline treating agent prior to hydrogenation. This treatment preferably follows the decobalting in the catalyst removal stage, though if desired it maybe concurrent, or under certain circumstances even precede that step. Preferably, however, the product from which the bulk of thev dissolved metal has been removed by heat treatment and stripping vis treated in a reflux zone with an aqueous solution of caustic, NazCOa, KOH, or thev like j'andf'as a result, aprecipitate of irony and cobalt 'hydroxide settles out from the solution. Because of the gelatinous nature of theV precipitate of iron hy droxide, ,the finely divided suspension and colloid-V ally kdispersed ycobalt and iron metal is removed by occlusion from the solution, and the resultant mixture may be allowed toA stand to allow for layer separation, andthe uppelflayermay then;

be sent to the hydrogenation stage without filtra-A tion, or only a rapid passage through a filter medium such as sand.

The present invention and its application will best be understood from the more detailed description hereinafter, wherein reference will be made to the accompanying drawing, which is a schematic representation of a system suitable for 'carrying out a preferred embodiment "of the invention. Referring now to the gure, as oleflnic compound having one carbon atom less than the number of carbon atoms in the desired resulting oxygenated compound is fed through feed line 4 to the bottom portion of primary reactor 2. The latter comprises a reaction vessel which may, if desired, be packed with non-catalytic material, such as Raschig rings, porcelain chips, pumice, and the like. Reactor 2 may be divided into discrete packed zones, or it may comprise but a single packed zone, or even if desired, may contain no packing.

The olenic feed preferably contains dissolved therein 1-3% by weight of cobalt naphthenate based on the olefin. Other compounds of cobalt or of iron, or their mixtures,may also be used. Simultaneously, a gas mixture comprising H2 and CO in the approximate ratio of 0.5 to 2 volumes of H2 per volume of CO is supplied through line 6 to primary reactor 2 and flows concurrently through reactor 2 with said olen feed. Reactor 2 is preferably operated at a pressure of about Z500-3500 p. s. i; g. and at a temperature of about 250-450 F., depending upon the olefin feed and other reaction conditions. The rate of flow of synthesis gases and olen through reactor 2 is so regulated that the desired conversion level of the olefin is obtained.

Liquid oxygenated reaction products containing catalyst in solution and unreacted synthesis gases are withdrawn overhead `from an upper portion of high pressure reactor 2 and are transferredthrough line 8 to cooler I0 in whichl any conventional means of cooling are employed, and from there via line l 2 to high pressure separator I4 where unreacted gases are withdrawn overhead through line I6, scrubbed in scrubber I8 of entrained liquid and cobalt carbonyl and used in any way desired. They may be recycled to syn-V thesis gas feed line 6 line 2|.

A stream of primary reaction product containing dissolved `,therein relatively high concentrationsof cobalt carbonyl and some Viron carbonyl is withdrawn from` separator I4 through line 22. A portion of "saidwithdrawn stream may be recycled if desired, to reactor 2 via line 24 to aidk in the cooling and maintenance of temperature control of the primary carbonyla-` tion stage. The balance of the primary reaction product, which'may comprise unreacted olefin, secondary reaction products, and dissolved catalyst and metal carbonyls as well as desired aldehydesyis withdrawn through pressure release valve 3S and line 38` and passed to catalyst removal or decobalting zone lll).l Within decobalter 40 the soluble cobalt carbonyl and a portion of ironl carbonyl formedfrom sources enumerated above'is removed' from the aldehyde'fproduced prior vto' high pressure hydrogenation Yinorder t'o prevent 'its decomposition in the hydrogenation Vstage with consequent reactor plugging and hydrogenation catalyst `contamination andinactivation withv metallic cobalt vor iron. Carbonyl vdecompositionis obtained by heating,l the aldehyde"productl by such'means'as closed s'ta'm.

via line 20 or purged via equipment, which .coils (not shown)l to .300.-350 at v.a pressure just vhigh enough to keep theV components in the lo-Wer may be employed. The product containing vcatalystinsolutionis injected into zone 40 Ythrough ,line 38 ata feed rate otabout 2-4 v.-/-v. /hr. I f desired, stripping gas, such as Ahydrogen, may be added through line 34 to aid in decreasing thev CO partial pressure. If desired, .itrnay beadvantageous to operate with two or more d ecobalters, switching the rstream from one to fanotheras the one 'in service accumulates excessive -quantities of mixed cobalt and iron metal. The gas stream comprising stripping vgas and CO vmay be removed overhead lfrom 40 through line Il 4v and used as desired.

The liquid aldehyde product now substantially tree of vdissolved cobalt carbonyl, but containing in solution Vironcarbonyl, some iron soaps and complexes, and possibly some cobalt compounds, and insuspension and dispersion, finely divided iron and cobalt metal, is withdrawn from catalyst removal zone 40 through line 42 and passed totreating` zone45. This latter may be a vesselV equipped with closed or open steam coils 4'.: and

lpreferably with means of agitation land reflux (notA shown). An aqueous vsolution Aof NaOH, preferably Iabout though it may vary from 5 to 50% is admitted through line AM3V at the rate of about 1-10 volumes reagent per 100. volumes product, Ymaintaining ragitation and, if desired, yunder reflux conditions. The mixture of product, precipitated iron hydroxide, and water is then passed to settling Zone 50. The lower layerhconsisti'ng ofspent caustic andsuspended iron hydroxide and voccluded nely divided metal, may be withdrawn through liner 52 and discarded. The'upperklaye'r, now `substantially free of dissolved land suspended iron and cobalt-...may be passed through line, 54 to washing-vzone156,

wherein it is'fthoroughlyagitated vwith vWater to removeranygalkaline treating agent, they upper product layenthen withdrawn through line `53 andY passed togiilter 60 if desired, for a simple ltration, though this may be omitted if desired.

The filtered solutiongis withdrawn from lter 60, passed through preheater 62 to theA bottom portion of hydrogenation reactor 'viavline 64. Simultaneously hydrogenis supplied to hydrogenation reactor 66 through line '68 'in proportions sufcient to convert aldehydes intofthe corresponding alcohols. Reactor 66 mayY contain a-massxof any conventional hydrogenationcatalyst, such as nickel, copper chromite, sulfactive catalyst such as tungsten, nickel or molybdenum suldes preferablysupported on carriers such as charcoal, pumice, andthe like. Reactor 6'6 Ais preferably operated at a temperature of about 400-50'0 iF., -Ipressure of about 2500-3500 p. s. i. g., and liquid feed rate of about 0.5-0.8 V./v.1/hr. f 'Y The products from the hydrogenation reactor and'y -unreacted hydrogen may be withdrawn overhead through line 'I0 and passed to the products recovery system and alcohols recovered all in a manner known per se.

The invention admits of numerous modifications apparent to those skilled in the art. Thus mention has not been made of various accessory normally are used in a commercial plant. Thus in the interest of good heat economy, various heat exchangers and economizers would be employed to utilize whatever heat is available in the most effective and efficient mannerV and, in order to control the process, pumps, compressors,l `valves, flow meters,v etc. would be included ,in the equipment. Also, instead of treating the primary reaction product with aqueous alkaline solutions yat room or reux temperatures, the decobalted product may `becontasted with the solid alkaline materials, such as NaOH or KOH, at elevated temperatures. EX- `cellent results 'have lbeen obtained when v.decobalted aldehydesl still f containing" signicant quantities of iron were treated with solid `KOH Eat the boiling point of the mixture. k'Furthermore, instead of yan alkali hydroxide, a strong organic base, such as tri or `tetrarnethyl .ammonium hydroxide may be employed as ya primary reaction product treating medium to' precipitate iron hydroxide. Theadvantage inthe use of this type ofv compound is that lits decomposition productsl are. gaseous and need not be removed from the product :layer by washing `in order -to prevent laterdanger of contamination of hydrogenation catalyst. Thus in the subsequent heating coils, tetramethyl ammonium hydroxide is decomposed to trimethyl amine land methyl alcohol, neither of which is a solid nor a contaminant, thus avoiding possible reactor inlet line and coil plugging or catalyst contamination. Thus this reagent as an aqueous solution may be passed into contacting zone through line 48 and after thorough mixing, the mixture of reagent, aldehyde product and precipitated metal hydroxides passed to -settling zone '50. The lower layer from 50 may be withdrawn, ltered, fortied with further reagent, and recycled `to treaterv 45. The washing stage, however, is `advantageously omitted, and the upper layer from settler may be passed directly to lter via bey-pass line 12.

The invention may be further illustrated by the following examples which help point up the-ald- 'vantages of the process hereinbefore described.

y Example I Primary reaction product from a semi-commercial plant comprising principally octyl aldehyde prepared from a' C7 olefin cut, and which has been passed through a catalyst removal zone 'and subjected to vcatalyst removal conditions, i. e., heating fora period of about 1 hour with :a closed steam `coil in the presence of H2 at a temperature of about 305 F. and wherein, as a result of such treatment, and subsequent Ifiltration through la sand liilter bed the soluble .cobalt concentration was reduced to about .003% and the iron' concentration to about 0.011 was reiiux'edfor about v1/4 hour yat 150 F.jwith 10% NaOI-I solution.` The resulting upper'layer after separation was 'found to contain no iron.

EavampleIIl Y o Primary reaction product obtainedas above, but beforel filtration, was agitated atroom (temperaturegwith 10%v NaOH for 5 minutes. As a result, the -amount'ofv iron in solution was .de-

creased from 0.039% before treatment, to 0.002%

after suchtreatment.

Example III l Another sample of the same material as above was treated for 5 minutes with lsolid KOH at a temperature of about F. The resulting iron yconcentration of the aldehyde product was only 0.001%.

Example IV Another sample of decobalted product subsethan .005% but an iro-n content of 0.01% was reiluxed with by volume of al Vmolar aqueous solution of tetramethy-l ammonium hydroxide. The resulting aldehyde product had an iron concentration of only 0.003%.

A sample ofthe octyl aldehyde product from the primary reactor was treated prior to passage through the catalyst removalzone with a 10% solution of 1 molar (CI-I3) 4.NOH under reux conditions. ,',I'he soluble iron concentration was reduced from 0.07% to 0.008%.

The foregoing description and examples though illustrating specific applications and resultsof the invention, are not intended to exclude modilcationsobvious to those skilled in the art and which Vare within the scope of the invention.

What is claimed is:

1. In a carbonylation process wherein carbon compounds containing olenic double bonds are contacted in an initial'reaction zone with carbon monoxide and hydrogen in the presence of a cobalt carbonylation catalyst under conditions to produce reaction products comprising oxygenated organic compounds containing at least one more carbon atom than said'olenic compounds, and wherein cobalt and iron carbonyls are dissolved in said reaction products, and the solution comprising saidreaction products and, dissolved carbonyls is transferred to a catalyst removal zone wherein the bulk of the carbonyls are decomposed under the influence of temperatures and pressures Vconducive to the decomposition of cobalt carbonyl in said catalyst removal zone, and wherein a liquid eiiluent comprising said oxygenated products as well as undecomposed iron carbonyl and dispersed nely divided cobalt is withdrawnfrom said last-named Zone and passed to a hydrogenation Zone, the step of removing dissolved iron compounds and dispersed solid from said eiiluent which comprises contacting the latter with a highly ionized alkaline treating agent in a treating zone the temperatures Iranging from room temperature to the boiling' point of said eiuent wherebyiron hydroxides are precipitated, and recovering from said treating'zone a liquid product comprising oxygenated organic compounds'substantially free of dissolved and dispersed cobalt and iron contaminants.

v 2. The process of claim 1 in which said treating agent is an alkaline reacting compound of an alkali metal.

3. The'. .process ofclaim 2 wherein said compound is added ito said treatingzone as anvaq'ueous solution. v

4. The process of claim 2 wherein said compound is added to said treating zone in solid form. 5. The process of claim 1 wherein said treating agent is an organic derivative of ammonia.

6. The process of claim 5 whereinsaid treating agentis la'tetra-alkyl ammonium hydroxide. 7. The process of removing undecomposed dissolved iron carbonyl and dispersed( iron and oobalt metal from the liquidq'efliuent from the catalystremoval zone of 'a carbonylation reaction process wherein olenic compounds are reacted with CO and H2 in the presence of a cobalt carbonylation catalyst which comprises passing said eiiiuent into a treating zone, passing" an aqueous solution of an alkali metal hydroxide into said zone, maintaining a temperature in said treating zone of from about 50-300 F., precipitating metal hydroxides from said eiiiuent, passing the mixture to a settlingy zone,` withdrawing a lower aqueous layer from said zone, passing an upper organic layer to a washing zone, and recovering an organic product substantially free of dissolved contaminants.

8. The process of claim 7 wherein said aqueous solution may have a concentration of 550% by Weight of alkali metal hydroxide.

9. The process of claim 7 wherein said eiiluent after washing is passed through a filtration zone prior to passing to a hydrogenation zone.

10. The process of claim 7 wherein said olen is a heptane fraction. Y

11. 'Ihe process of removing undecomposed dissolved iron carbonyl and dispersed iron and cobalt metal from the liquid effluent from the catalyst removal zone of a carbonylation reaction process wherein olens are reacted with CO and H2 in the presence of a cobalt carbonylation catalyst which comprises passing said eiiiuent into a treating zone, passing an vaqueous solution of tetramethyl ammonium hydroxide into said zone, precipitating metal hydroxides and occluding dispersed metals from solution, passing the mixture to a settling zone, and recovering a primary carbonylation reaction product substantiallyfree of dissolved'and dispersed iron and cobalt.

12. 'I'he process of claim 11 wherein the concentration of said aqueous solution is about 1 molar.- y v Y* 13. The process of claim 1 wherein saidl treating agent is an alkali metal hydroxide.

14. 'The process of claim 1 wherein said treating agent is an alkali metal carbonate.

A CECIL H. HALE.

REFERENCES CITED The vfollowing references are of record in the iile 'of thispatent:

A Y UNITED STATES PATENTS Number Name Date 2,508,743 Bruner May 23, 195,0 2,509,878 Owen May 30, 1950 OTHER. REFERENCES Berichte, vol. 56B (1923). pagesY 2264-2267. a 

1. IN A CARBONYLATION PROCESS WHEREIN CARBON COMPOUNDS CONTAINING OLEFINIC DOUBLE BONDS ARE CONTACTED IN AN INITIAL REACTION ZONE WITH CARBON MONOXIDE AND HYDROGEN IN THE PRESENCE OF A COBALT CARBONYLATION CATALYST UNDER CONDITIONS TO PRODUCE REACTION PRODUCTS COMPRISING OXYGENATED ORGANIC COMPOUNDS CONTAINING AT LEAST ONE MORE CARBON ATOM THAN SAID OLEFINIC COMPOUNDS, AND WHEREIN COBALT AND IRON CARBONYLS ARE DISSOLVED IN SAID REACTION PRODUCTS, AND THE SOLUTION COMPRISING SAID REACTION PRODUCTS AND DISSOLVED CARBONYLS IS TRANSFERRED TO A CATALYST REMOVAL ZONE WHEREIN THE BULK OF THE CARBONYLS ARE DECOMPOSED UNDER THE INFLUENCE OF TEMPERATURES AND PRESSURES CONDUCIVE TO THE DECOMPOSITION OF COBALT CARBONYL IN SAID CATALYST REMOVAL ZONE, AND WHEREIN A LIQUID EFFLUENT COMPRISING SAID OXYGENATED PRODUCTS AS WELL AS UNDECOMPOSED IRON CARBONYL AND DISPERSED FINELY DIVIDED COBALT IS WITHDRAWN FROM SAID LAST-NAMED ZONE AND PASSED TO A HYDROGENATION ZONE, THE STEP OF REMOVING DISSOLVED IRON COMPOUNDS AND DISPERSED SOLID FROM SAID EFFLUENT WHICH COMPRISES CONTACTING THE LATTER WITH A HIGHLY IONIZED ALKALINE TREATING AGENT IN A TREATING ZONE THE TEMPERATURES RANGING FROM ROOM TEMPERATURE TO THE BOILING OINT OF SAID EFFLUENT WHEREBY IRON HYDROXIDES ARE PRECIPITATED, AND RECOVERING FROM SAID TREATING ZONE A LIQUID PRODUCT COMPRISING OXYGENATED ORGANIC COMPOUNDS SUBSTANTIALLY FREE OF DISSOLVED AND DISPERSED COBALT AND IRON CONTAMINANTS. 